Hand-held power tools are used for a number of purposes. One type of hand-held power tool is known as a die grinder. Die grinders are typically high speed power tools having a rotating attachment used for conventional grinding, cutting, or buffing of an element, such as where a tool is used to remove excess material, e.g., a weld bead, from a metal work piece.
In operating die grinders and other power tools, the operator must use caution to remain safe and healthy. One concern that must be addressed by the power tool operator, or his or her employer, is the prevention of disorders of the hands and arms when performing tasks consisting of highly repetitive motion and/or exposure to extended vibration. Cumulative trauma disorders such as carpal tunnel syndrome and tendinitis can be caused or aggravated by repetitious, forceful exertion of the hands and arms. Vibration may also contribute to a condition called Raynaud's Syndrome. These disorders may develop gradually over periods of weeks, months, and years. Although, it is not presently known to what extent exposure to vibrations or repetitive motions may contribute to these disorders, it might be advisable to minimize vibration and repetitive motions when possible.
In protecting a power tool operator, such as a die grinder operator, it may be necessary for the operator or employer to take steps to prevent disorders of the hands and arms mentioned above. The steps may include repositioning the work piece or redesigning the workstation, reassigning an operator to other jobs, rotating jobs, changing the work pace, and/or changing the type of tool used so as to minimize stress on the operator.
In operating conventional hand-held die grinders, the operator places a portion of the die grinder into the palm of the operator's hand, and depresses a throttle mechanism. The throttle causes an element to rotate, such as a grinding element, which may then be placed into contact with the work piece. This type of conventional die grinder, such as that shown in U.S. Pat. No. 3,809,179, to Delaney, Jr. et al., has a single longitudinal axis. In grabbing the straight die grinder, it is common for the operator to bend his or her wrist in ulnar deviation to avoid being exposed to the sparks, swarf, and grinding residue resulting from the application of the rotating element, such as an abrasive wheel or carbide burr, to the work piece. The operator may also grasp the tool and angle it to engage the work piece with the tool in an orientation that allows clear vision and allows a desired result to be obtained. Continued operation in ulnar deviation of the wrist is generally not recommended.